Family 8 xylanases such as from Pseudoalteromonas haloplanktis and the
alkaliphile B. halodurans had a more positive effect in baking than the commonly
used commercial enzyme [203, 204]; however, it is not yet clear if this is due to
selective action on the water-unextractable hemicellulose. The use of xylanases is
also beneficial in biscuit baking due to its ability to make cream crackers lighter and
improve its texture and tastiness [202].
The use of hemicellulases in food processing can improve the nutritional quality
of food. For instance, due to their bioactive nature, XOS and MOS are being used
as dietary supplement that infer prebiotic, antioxidant, and potential immunemodulating properties [47, 48]. These oligosaccharides can be obtained directly by
treating xylan- or mannan-containing food with xylanase or mannanase. Moreover,
the nutritional quality of cereal-based foods can be improved upon using xylanases
that modify the dietary fiber. Water-soluble dietary fibers have beneficial health
effects such as lowering plasma cholesterol which is associated to coronary heart
disease and type 2 diabetes [205, 206]. Xylanases improve the level of water-soluble
arabinoxylans in fiber-enriched bread [207] and pasta [208] and hence infer health
benefits.
Hemicellulases are important processing aids in industrial wheat gluten and
starch separation processes. Xylanases which act on soluble arabinoxylan rapidly
decrease the viscosity of wheat flour slurries and have shown excellent performance
in the wheat separation process, which results in higher gluten and starch yields and
improved gluten quality [209]. Hemicellulases have also been successfully tried in
plant oil extraction [210, 211].
6.8 Beverages
In brewing industries, the viscosity created by soluble arabinoxylans may pose wort
filterability and haze formation problems. The use of xylanases that degrade watersoluble arabinoxylans decreases wort viscosity and leads to an increased filtration
rate and reduced beer haze formation [162]. Xylanases together with cellulase and
pectinase are used to clarify must and juices and liquefy fruits and vegetables
[19]. This enzymatic treatment helps to stabilize the fruit pulp, reduce viscosity,
and remove substances that may cause cloudiness in the concentrate [156, 202].
Mannanases are used to reduce the viscosity of coffee extracts in production of
soluble coffee and clear fruit juices and wines [114].
6.9 Other Applications
Xylanases and mannanases have also been tried in many other applications.
Xylanases have been considered in the synthesis of fine chemicals [212, 213].
Since xylan is readily soluble in alkaline condition, a better synthetic efficiency is
278
G. Mamo
alkaliphile B. halodurans had a more positive effect in baking than the commonly
used commercial enzyme [203, 204]; however, it is not yet clear if this is due to
selective action on the water-unextractable hemicellulose. The use of xylanases is
also beneficial in biscuit baking due to its ability to make cream crackers lighter and
improve its texture and tastiness [202].
The use of hemicellulases in food processing can improve the nutritional quality
of food. For instance, due to their bioactive nature, XOS and MOS are being used
as dietary supplement that infer prebiotic, antioxidant, and potential immunemodulating properties [47, 48]. These oligosaccharides can be obtained directly by
treating xylan- or mannan-containing food with xylanase or mannanase. Moreover,
the nutritional quality of cereal-based foods can be improved upon using xylanases
that modify the dietary fiber. Water-soluble dietary fibers have beneficial health
effects such as lowering plasma cholesterol which is associated to coronary heart
disease and type 2 diabetes [205, 206]. Xylanases improve the level of water-soluble
arabinoxylans in fiber-enriched bread [207] and pasta [208] and hence infer health
benefits.
Hemicellulases are important processing aids in industrial wheat gluten and
starch separation processes. Xylanases which act on soluble arabinoxylan rapidly
decrease the viscosity of wheat flour slurries and have shown excellent performance
in the wheat separation process, which results in higher gluten and starch yields and
improved gluten quality [209]. Hemicellulases have also been successfully tried in
plant oil extraction [210, 211].
6.8 Beverages
In brewing industries, the viscosity created by soluble arabinoxylans may pose wort
filterability and haze formation problems. The use of xylanases that degrade watersoluble arabinoxylans decreases wort viscosity and leads to an increased filtration
rate and reduced beer haze formation [162]. Xylanases together with cellulase and
pectinase are used to clarify must and juices and liquefy fruits and vegetables
[19]. This enzymatic treatment helps to stabilize the fruit pulp, reduce viscosity,
and remove substances that may cause cloudiness in the concentrate [156, 202].
Mannanases are used to reduce the viscosity of coffee extracts in production of
soluble coffee and clear fruit juices and wines [114].
6.9 Other Applications
Xylanases and mannanases have also been tried in many other applications.
Xylanases have been considered in the synthesis of fine chemicals [212, 213].
Since xylan is readily soluble in alkaline condition, a better synthetic efficiency is
278
G. Mamo